Tube of thermoplastic derivatives of cellulose



Feb. 8, 1938. w. SALEMME 2,108,022

TUBE OF THERMOPLASTIC DERIVATIVES OF CELLULOSE Original Filed May 24,1934 2 Sheets-Sheet l Elma/WW Snow M45 W. SALEMME Feb. 8, 1938.

TUBE OF THERMOPLASTIC DERIVATIVES OF CELLULOSE Original Filed May 24,1934 2 Sheets-Sheet 2 Patented Feb. 8, 1938 TUBE F THERMOPLASTICDERIVATIVES OF CELLULOSE William Salcmme, West Orange, N. J assignor toCelluloid Corporation, a corporation of New Jersey Original applicationMay 24, 1934, Serial No. 727,-

210. Divided andthis application July 8, 1936,

' Serial No. 89,549

9 Claims.

This invention relates to tubes such as fountain pen and pencil barrels,wire conduits, etc. and

to cylindrical tubes for blowing into irregular shaped articles such asbrush handles, etc., that contain a thermoplastic composition which maycomprise a derivative of cellulose with or without a plasticizer.

This application is a division of my application S. No. 727,210, filedMay 24, 1934.

An object of the invention is the economic and expeditious production oftubes from thermoplastic derivatives of cellulose. Another object of theinvention is the production of tubes having desirable propertiesheretofore unattainable. Other objects of the invention will appear fromthe following detailed description.

In the drawings wherein like numbers refer to the same or correspondingelements:

Fig. 1 is a perspective view partly in section of a device constructedaccording to this invention.

Fig. 2 is a perspective view of a device for cementing the edges of aformed tube.

Fig. 3 is a perspective view of a sheet of material containing a windowstrip.

Fig. 4 is'a perspective view of atube formed according to this inventionand containing the window strip.

Fig. 5 is a perspective view of a sheet having angled sides forobtaining a butt joint in the formed tube when working with heavy orthick material.

Fig. 6 is an end view of a tub I formed of a sheet having angled edges.

Fig. 7 is a perspective view of a thin sheet having right angled edges.

Fig. 8 is an end view of a tube formed from a sheet as shown in Fig. '7.

Fig. 9 is a side view of an optional shaping member to be used in thedevice shown in Fig. 1.

Fig. 10 is' an end view of the shaping member not be obtained beforewlthrod stock, sheet stock, by the extrusion or casting methods.

' The spiral tube was not satisfactory for cer tain purposes on accountof the spiral seam. A straight line or lateral .seam is lessconspicuous, but the molding methods generally prescribed foraccomplishing this are not practical or feasible. The fins of the twomolded seams have to be scraped ofi, smoothed and the joint is oftentimes quite weak, owing to the lack of cement during the moldingoperation. The molded seams also showa strained condition whichmanifests itself in unevenness when the tube is subjected to any hightemperatures, such as hot water. When molded articles from which thefins have been scraped are immersed in hot water,

'there is a tendency for the tube to collapse which reveals the strainedcondition. In the case of spiral tubing it is necessary to, applyuniform tension or twist to insure good welding. The result is that. theproduction of satisfactory tubing depends almost entirely upon theoperators technique. Thisinvention is less subject to the personalelement. It makes a very strong tube, which can be demonstrated by thefact that a tapered steel mandrel hammered into the tube fails to pry itopen and also by the fact that the tube may be immersed in boiling waterfor long periods of time without collapsing at the seam. Furthermore,this invention \is unlimited in the size of tubes that may/ be. formed.Thus the method can be applied to the manufacture of tubes of from below& of an inch in diameter and .0075 inch in g uge to" tubes of above 2inches in diameter i and .25 inch in thickness. Gauge of sheet stock anddiameter of tubing are not necessarily dependent on each other. By thisinvention a small diameter tube may be made of heavy stock and a largediameter tube may be made of thin gauge stock. According to my inventionI cut or form a strip of a thermoplastic material, especially athermoplastic derivative of cellulose, of the width equal to thecircumference of the desired tube. This strip of material is immersed inwater or other suitable heating medium until the material issufiiciently soft to readily bend and remain bent without a tendency tospring back to original position. When the thermoplastic strip issufiiciently soft, which ordinarily requires only a few minutes inboiling water, it is drawn by one end, which is preferably tapered andbored, by any suitable means such as by a strong wire, and pulledsteadily through a cold water jacketed metal tube whose diameter andinternal-configuration is varied according to the size and shape of thetube desired. In making tubes of heavy gauge strips, the sides of thestrips are preferably cut at an angle or scarfed to form a full edge toedge abutment when twisted to a tube shaped article. Owing to the totalimmersion of the strip in hot water there is no stress or strain alongthe edges. After forming, the tubes are dried and may then be cementedby immersing, or at least immersing the seam of, the tube lengthwise ina trough bath filled with a solvent for the material and opening theseam with a blade to insure the penetration of the solvent into theseam. Instead of a solvent any other adhesive agent may be employed. Theformed tube may then be allowed to dry and may be subjected to any ofthe finishing operations such as straightening and/or stretching over amandrel, drawing and grinding. The drawing operation may be merelyredrawing the tube through a device similar to the one in which it wasformed or the tube may be stretched over a mandrel, the loaded mandrelbeing inserted in a container, pipe, etc. through which steam iscirculated to render the tube soft. The tube and mandrel are then pulledthrough a cold water jacketed tube of a diameter less than the formedtube after which the tube is removed from the mandrel.

The stretching operation may be performed in a similar device to thetube forming device. That is, the softened tube is drawn through a coldmetallic tube of a diameter less than that of the formed tube. Thisstretching operation is also applicable to. the smoothing out andreducing the diameter of solid rods which are softened with heat andpulled through the cold jacketed cylinder in the same manner as thetubes.

Further according to my invention I construct a device that is eflicientand is both simple to make and use, which device in part resembles anordinary laboratory condenser with the ends of the tube cut off near thejacketed portion. There may also be provided a bath or oven or othermeans of supplying the necessary heat to soften the thermoplasticmaterial and a second bath for cementing the formed seams. Any suitablemeans may be used for drawing the tubes through the jacketed shapingcylinder.

All parts of the device that come in contact with the thermoplasticmaterial or the reagents used therewith, such as the bath containers,the shaping cylinder, etc., may be made from stainless steel or steelcoated with a protective alloy or metal such as chromium, nickel and thelike.

Any suitable thermoplastic material may be shaped to a tube by thisinvention. The thermoplastic derivatives of cellulose, however, lendthemselves especially well. Under the term thermoplastic derivative ofcellulose may be included cellulose nitrate, organic esters ofcellulose, cellulose ethers and the mixed ethers and/or esters ofcellulose. Examples of organic esters of cellulose are celluloseacetate, cellulose formate, cellulose propionate and cellulose butyrate,while examples of cellulose ethers are ethyl cellulose, methyl celluloseand benzyl cellulose. Such mixed esters may be employed as the nitrocellulose acetate. Also mixtures of two or more derivatives of cellulosemay be employed in the same plastic material, for example a mixture ofcellulose acetate and cellulose nitrate.

The cellulose derivative may contain plastioizers to make them more,readily susceptible to the action of heat. The plasticizer may be anysuitable one for the particular cellulose deriva.

tive or mixture of cellulose derivatives employed. The plasticizers maybe any of the high boiling solvents or softening agents as, for example,the aryl sulphonamides such as para ethyl toluol sulphonamide, the alkylphthalates such as dimethyl phthalate, the dialkyl tartrates such asdibutyl tartrate, the alkoxy esters of polybasic organic acids such asdiethyoxy ethyl phthalate, the polybasic acid esters of the mono alkylethers of polyhydric alcohols such as diethylene glycol ethyl etherester of phthalic acid, the alkyl esters of phosphoric acid such astriethyl glycol phosphate, the aryl esters of phosphoric acid such astricresyl phosphate, the mixed alkyl and aryl phosphates, and camphor.The plasticizers may be used alone or in combination with others. Thequantity of plasticizers employed may vary within very great limits,say, from 10 to 75 parts by weight per parts of the cellulose derivativein the finished product.

The plastic material may contain besides the derivative of cellulose andplasticlzer, efiect materials such as pigments, filling materials,soluble or insoluble dyes or lakes, fire retardants, sizes and oilymaterials. Examples of pigments and filling materials are metallic saltsand oxides such as titanium oxide, zinc oxide, mercurous chloride,bismuth oxy chloride, powdered metal such as powdered aluminum andbronze, powdered nonmetallic substances such as logwood, lampblack andfish scale. Examples of fire retardants are beta chlornaphthalene,triphenyl phosphate and tricresyl phosphate. Examples of sizes are thewaxes, resins and synthetic resinous material. Examples of the oilymaterials are the animal, vegetable and mineral oils such as castor oil,olive oil, neats foot oil and petroleum jelly, glycerine, glycols andthe derivatives and substitution products of the polyhydric alcohols.

The strips of thermoplastic material may be cut from any suitable sheetsor slabs. The strips may be transparent, translucent or opaque and maybe colorless or may have any suitable pigment, dye or effect materialincorporated therein to produce mottled, variegated or otherdifferential eiTects or pearl-like or nacreous appearance. Instead ofusing stock entirely of the same material, there may be used compositedor laminated plastic sheets, making it possible to obtain variousartistic effects, such as pearl, cloisonn, snakeskin and the like, whichcannot be obtained in any other manner. This modification also makes itpossible to use as base stock, materials which would be unsuitable forsurface eiTccts because of color or inferiority of stock, but which, bymeans of overlays, can be made to present an agreeable surface or color.

The'composite sheets or strips for use in making tubes in accordancewith the present invention may be produced in any suitable manner. Forexample, a pearl, onyx or any suitably colored or patterned elTect isveneered with a sheet of colored or colorless transparentnitrocellulose, cellulose acetate or other cellulose derivative so thatin the subsequent operations the transparent sheet will protect theunder-layer containing the pattern or color effect. Also a. transparentsheet of about 20 one thousandths of an inch may be composited over afabric containing a design and a base sheet of material of any color tomake up a total thickness of 60 one thousandths of an inch. The fabricmay be replaced by a lithographed thin sheet or by a celluloid orsimilar sheet previously impressed with a finish such as morocco orsnakeskin. Further, the sheets and slabs may be formed by any othersuitable process as more fully described in U. S. Patents Nos. 1,864,794issued June 28, 1932; 1,812,283 issued June 30, 1931; 1,814,641 issuedJuly 14, 1931; 1,845,457 issued February 16, 1932; 1,899,053 issuedFebruary 28, 1933; 1,929,113 issued July 25, 1933; and 2,054,848 issuedSeptember 22, 1936.

The strips Ill of suitable width, thickness and length are tapered atone end as shown at H in Fig. 1. They are then placed in a tank 12containing a liquid [3 that has little or no chemical action on thethermoplastic derivative or other ingredients of the strip material. Theliquid may be water or other suitable liquid. Means, not shown, such asan electric resistance or inductance coil, steam coil, open flame orother means may be employed for raising and maintaining the liquid at anelevated temperature, which temperature will depend upon the softeningtemperature of the thermoplastic material.

The strip material after being softened is attached, as by a hook i l, atong member, or other gripping element, to a cable l5 or other suitabledrawing element. The cable or drawing member is then caused to pull thestrip through a metal tube '59 that is cooled by a fluid flowing througha space formed by a jacket I! surrounding the tube i6. The jacket ispreferably insulated with a coating of asbestos l8, cork or othersuitable coating and is equipped with an entrance I9 and exit forcirculating within the space between the jacket and the tube 16 a coldfluid that may be water, brine or other suitable cooling agent. Thecable or drawing member l5 may be caused to exert an even pull on thestrip by winding said cable on a roller 2| by means of the hand crank22, which in working on long strips, may be supplanted by an electricmotor or other suitable source of positive power, or by a weightattached to one end of the cable which is passed over a pulley.

The metallic shaping tube l6 may be tapered or funnel shape for a shortdistance at the entrance and to permit easy threading of the cable andstrip thereto. The tapered part is preferably short such that thematerial is immediately chilled as soon as it has reached its desiredshape. The shaping tube may be round in cross section as shown in. Fig.1, or it may be elliptical, square, polygonal, heart shape, etc. Ifdesired, tubes with more elaborate cross sections may be formed byemploying a shaping tube, as shown in Figs. 9 and 10, which is round atthe entrance end 23 and any suitable shape at the exit end 24, forexample, star shaped.

After the strip material is formed into a tube, it may be submerged in asolvent bath 25 contained in a suitable trough 26 having means 21 forholding the tapered end I! of the tube. While the tube is submerged inthe solvent, a blade 28 may be drawn along the tube to momentarily openthe seam and allow the abutting edges of the thermoplastic derivative,to come in contact with the solvent. The blade is easily inserted in theseam by reason of the tapered end if of the tube. The tube being set andfree of stresses and strains due to its method of formation closestightly together again at the rear of the blade. Instead of employing asolvent bath, there may be employed an adhesive in the form of a liquidor paste which may be applied onto the edges immediately back of theblade. When employing a solvent bath, the tube upon springing back toclosed position, after the passing of the blade, forms a perfect weldwhich upon drying becomes as stout as the remaining part of the tube.

After treatment in the solvent liquid or cementing material, the tubemay be seasoned in a normal manner. Examples of suitable solventmaterial are chloroform, acetone, a mixture of acetone and ethyl ormethyl alcohol ethylene dichloride, a mixture of ethylene dichloride andethyl or methyl alcohol, and a mixture of methyl chloride and ethyl ormethyl alcohol. Examples of cementing materials that may be applied tothe opened edges are solutions of organic derivatives of cellulose,vinyl resin products. cresylic resin products and rubbercontainingadhesives.

When form ing tubes of relatively thin sheets, the sides of the stripmay be cut at right angles to the face of the strip, as shown at 39 onFig. '7, which will form a full radial abutting Joint as shown in Fig.8. However, when forming tubes of relatively thick sheets, the sides ofthe strip should be scarfed as at 3| on Fig. 5 such that when the stripis curved the full width of the edge will contact with the opposite edgeas shown in Fig. 6 in a radial joint.

For tubes that are to contain liquids or powders such as fountain penbarrels, etc., a block may be formed of three layers of differingcomposition, the middle layer being a clear transparent material. Thisblock is then sliced to form strips used in making tubes. In this way atube of opaque highly decorative material may be formed that has atransparent window running lengthwise thereof allowing visibility intothe tube. Thus, in Fig. 3 is shown a strip composed of two opaque sidestrips 32 joined by a highly transparent strip 33. When such a strip isformed into a tube the transparent strip forms a window through whichthe height of material in the tube may be located.

The device may be operated as a single unit or a tank of, say boilingwater, may be provided at the ends of a batteryof the cold waterjacketed shaping types. All the operator has to do is hook the cablesthrough the holes in the tapered ends of the strips and the wirespulled. with an even tension by suitable means. The shaping tubes mayvary from 6 inches to 2 feet or more in length, depending upon the typeand weight of the material worked. It is highly important that thesoftened, heated thermoplastic strip be immediately cooled as it entersthe coolers to prevent any stretching and for preventing the developmentof stresses. Therefore, it is essential that there be good circulationof cooling fluid surrounding practically the entire length of the tube,particularly at the entrance end.

When making optical tubing it is not necessary to apply cement to closethe seam. The optician buys the tubing .with open seam, inserts themetal rim or rod and then immerses the entire article in a solvent. Theoptical tubing thus made is unique and attractive as it may present anover-all pearl or decorative surface not present in stuffed rods. Afurther method of forming a rod covered article is to feed the metallicrod simultaneously with the. strip to the shaping tube such that thethermoplastic strip is wrapped around the metal rod.

Tubes made according to this invention lend themselves admirably toblowing shaped articles or forming operations, making possibly manyconfigurations which are entirely new, particularly for shaving brushhandles and like objects. Pearl stripes or laminations and the luster ofsame are uniform all-around and the seam is very hard to detect. Theseshaped, blown or tube formations may be used for fountain pens, towelbars, bed stands, golf shafts, broom sticks, billiard cues, etc. or forlining for pipes and tubes and insulation purposes.

The sheet material from which the strips are cut may be laminated sheetstock with or without inlaid material and coloring matter between thesheets. Thus, tubes having fiber or flexible metal inlays may be formedand used to advantage.

The tubes after being formed and their seams sealed may be softened byheat and drawn through a shaping tube of slightly smaller diameter thanthe tube in which they were formed. By this means there is a drawingaction which reduces the diameter of the tube and also smooths out anyirregularities on the surface. This action also aids in obliterating anyvisible seam. Solid extruded rods may also be drawn through such adevice to reduce their diameter and smooth their surface therebyeliminating any necessity of grinding and polishing the small rods toobtain a smooth surface of the desired sized rod and to greatly reducethe necessity of grinding seams on large and heavy tubes and rods.

The blown or shaped articles made from the tubes or the tubes themselvesmay be filled with any suitable filling materials to form solidarticles. Likewise, the tubes may be stretched over solid wooden orartificial material cores for umbrella and cane handles, etc.

Hollow articles made in accordance with this invention are characterizedby the fact that when they are submerged in boiling water for fiveminutes they are free of collapsing or caving in at the seams andundesirable distortions.

Moreover, unless they are: given a preshrinking treatment, such articleswhen subjected to boiling water for five minutes shrink appreciably,from 3 to usually 5 to 15%, in length, due

to release of longitudinal stresses set up during the above describedstretching operations.

It is to be understood that the foregoing detailed description anddrawings are merely given by way of illustration and many alterationsmay be made therein without departing from the spirit of my invention. 1

Having described my invention,'what I desire to secure by Letters Patentis:

1. A hollow article of thermoplastic material having abutting edgesjoined in a permanent straight lateral seam, said article beingsubstantially free of residual stresses tending to cause undesirabledistortion and collapsing.

2. A hollow article of thermoplastic derivative of cellulose havingabutting edges joined in a permanent straight lateral seam, said articlebeing substantially free of residual stresses tending to causeundesirable distortion and collaps ing.

3. A hollow article of thermoplastic material having abutting edgesjoined in a permanent straight lateral seam and being transparent in atleast a portion thereof, said article being substantially free ofresidual stresses tending to cause undesirable distortion andcollapsing.

4. Fountain pen barrels and the like of thermoplastic material havingabutting edges joined in a permanent straight lateral seam, saidarticlebeing substantially free of residual stresses tending to causeundesirable distortion and collapsmg.

5. Fountain pen barrels and the like of thermoplastic derivative ofcellulose having abutting edges joined in a permanent straight lateralseam, said article being substantially free of residual stresses tendingto cause undesirable distortion and collapsing.

6. A hollow article of thermoplastic material having abutting edgesjoined in a permanent straight lateral seam, said article beingsubstantially free of residual stresses tending to cause undesirabledistortion and collapsing and having residual stresses tending toshorten the length thereof.

'7. A hollow article of thermoplastic deriva tive of cellulose havingabutting edges joined in a permanent straight lateral seam, said articlebeing substantially free of residual stresses tending to causeundesirable distortion and collapsing and having residual stressestending to shorten the length thereof.

8. Fountain pen barrels and the like of thermoplastic material havingabutting edges joined in a permanent straight lateral seam, said articlebeing substantially free of residual stresses tending to causeundesirable distortion and collapsing and having residual stressestending to shorten the length thereof.

9. Fountain'pen barrels and the like of thermoplastic derivatives ofcellulose having abutting edges joined in a permanent straight lateralseam, said article being substantially free of residual stresses tendingto cause undesirable distortion and collapsing and having residualstresses tending to shorten the length thereof.

WILLIAM SALEMME.

